Two federal agencies want changes in a key portion of the proposed Illiana Expressway, a stance likely not enough to kill the already controversial road but one that could complicate its finances and spark a legal fight.

In separate comments filed this week, the U.S. Department of the Interior and the Environmental Protection Agency objected to a proposed Illiana interchange with State Route 53 in Will County. (Read the Interior Department comments below.)

The interchange is near CenterPoint Properties Trust's development of the old Joliet armory site, potentially a huge source of truck traffic for the Illiana. But it's also near the Midewin National Tallgrass Prairie, which is protected by federal law and which both agencies said would be jeopardized by the big road.

Both recommended the state instead "choose Design Option 6," which calls for no intersection with State Route 53 at all.

The comments immediately were seized on by longtime Illiana critic Howard Learner, head of Chicago's Environmental Law and Policy Center.

FEDERAL LAW

Federal transportation law generally bans developments that would hurt areas such as the tallgrass prairie unless there is no "feasible and prudent alternative," Mr. Learner said. In this case, he said, there is an alternative: dropping the interchange. But that "could lead to less traffic to a road that already has financial viability concerns."

Such concerns were raised by the staff of the Chicago Metropolitan Agency for Planning, though CMAP's policy committee eventually overruled the staff and voted to endorse the road.

Guy Tridgell, a spokesman for the Illinois Department of Transportation, Illiana's main advocate, noted that the comments were made in regard to the draft Environmental Impact Statement IDOT has issued on the road.

"We will consider, evaluate and respond to all comments received," he said.

Mr. Tridgell also noted that the U.S. EPA could have issued a far sterner formal "environmental objection" to the road, and he emphasized that the final federal decision to green-light the road will be made by the U.S. Department of Transportation.

But the IDOT spokesman also strongly suggested his department wants some sort of intersection between the Illiana and State Route 53. "We hope to see an interchange” there, he said. "That's our preferred alternative."

Mr. Learner responded that the Interior and EPA comments are "not a deal-stopper, but they could be the basis for a federal lawsuit. "If IDOT says they're going to stubbornly stick with their original plan, that's an issue the courts ultimately will decide."